Depending on your needs, here are a couple of ways:
IF EXISTS (SELECT * FROM TABLE WHERE COLUMN = 'SOME VALUE')
--INSERT SOMETHING
ELSE
--INSERT SOMETHING ELSE
Or a bit longer
DECLARE @retVal int
SELECT @retVal = COUNT(*)
FROM TABLE
WHERE COLUMN = 'Some Value'
IF (@retVal > 0)
BEGIN
--INSERT SOMETHING
END
ELSE
BEGIN
--INSERT SOMETHING ELSE
END